Pro that is for some one else to proclaim. I have in the past made my living doing Auto Body and Paint. People in this line of work have different process that they are comfortable using, it is actually a personal preference. There are may lines and types of product to use. My father still uses Lacquer yeh Lacquer GARBAGE but that is by today's standard. In the day, it was the best. When I work on glass, I seal it up with DP Epoxy then go to the filler, after the shape is right a coat of DP fallowed by 2K, then the sand and 2K, if you have done a good job, final sand, seal and paint, DCC base Poly clear. How much product you will use is dependent on your overall ability. 1gal unmixed DP, Bondo and 2K is a great start. Paint will take 1gal spray-able, Clear 2gal spray-able as you will sand and polish about 1/3 of what you spray on, off. Hope this is what you are looking for.
Steve the other half of Angela